I have had this happen twice since a few weeks ago. I have installed 5.5.3 since then and then upgraded to 64 bit so I am not sure which one of those triggered it. It don’t remember it happening when I was running the 32 bit 5.5.2. It did finish after about 3-5 minutes. I don’t have any content beyond the stock content so I can see how someone with a lot of extra media could be waiting a very long time.
I am fairly certain there have been other posts about this. I don’t remember ever seeing an answer though. I couldn’t find the old topics becuase the search function on the forum is not very good.
J.L.
EDIT. I found one of the topics I saw about this